CROSSTALK BETWEEN FLOWERING AND DEFENSE MEDIATED BY THE SUNFLOWER TRANSCRIPTION FACTOR HAHB10

DEZAR CA, GIACOMELLI JI, BONAVENTURE G, MANAVELLA PA, RE D, ALVES-FERREIRA M, BALDWIN I AND CHAN RL

Carlos Paz

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

ABSTRACT HAHB10 is a member of the sunflower subfamily II of HD-Zip transcription factors. Transgenic plants ectopically expressing this gene were previously obtained showing an early flowering and a shorter life cycle. In this work we show that these plants exhibit higher susceptibility to herbivorous attack compared to control plants and increased SA levels suggesting a major tolerance to pathogens. On the other hand, the promoter region of this gene was isolated and fused to the GUS reporter in order to transform Arabidopsis thaliana plants. In normal growth conditions, this promoter directs the expression in leaves, roots and particularly in stems and anthers during the reproductive stage. When the transformed plants were subjected to wounding or chewing the expression of the reporter was inhibited while when the plants were subjected to P. syringae attack, it was notably increased. Concomitant results were obtained in sunflower leaves either WT or transiently transformed. Transcriptome analysis carried out with the plants expressing the HAHB10 cDNA indicates that several genes involved in the transition from the vegetative to the reproductive stage are strongly induced. Among them, FT, AGL9 and AGL8 showed significant differences. We propose that HAHB10 plays a role in the coordination of flowering time and defense responses through a cross talk between SA and other signaling pathways.